The present invention relates to an improvement in a device for drawing various kinds of drawable materials of thermoplastic resin, such as fibers, films, bands and sheets (hereinafter merely abbreviated as xe2x80x9cdrawable thermoplastic resin materialsxe2x80x9d or xe2x80x9cdrawable materialsxe2x80x9d).
Drawable thermoplastic resin materials are generally drawn in a post-step in order to improve their physical properties such as strength, Young""s moduli, etc. Heretofore, the following devices were used for such drawing.
{circle around (1)} A device for drawing a drawable material under contact heating by passing the drawable material through a metal heating roll, a metal hot plate, or the like.
{circle around (2)} A device for drawing a high-molecular material by a non-contact heating method while the high-molecular material moves in a pressure-resisting vessel filled with a pressurized fluid, via a supply port and an outlet in the front and rear of the vessel, wherein the supply port and the outlet need to be selected to be such narrow gaps that the pressurized fluid does not leak (as described in JP-A-60-193632).
{circle around (3)} A device for drawing a string by another non-contact heating method-while the string moves in a pressurized steam treatment chamber, wherein multiple stages of labyrinth nozzles are formed in the front and rear of the treatment chamber so that a pressure loss of high-pressure steam is used to prevent steam pressure in the treatment chamber from being lowered to thereby prevent steam from leaking (as described in JP-A-6-57572).
In the device {circle around (1)} using contact heating, both the drawing speed and magnification were limited. In the device {circle around (2)}, there was a difficulty that the drawable material to be drawn was apt to be damaged because the gaps were selected to be as narrow as possible to prevent the pressurized fluid from leaking. In the device {circle around (3)}, it was necessary to increase the number of labyrinth nozzles if the pressure loss was increased to keep the treatment chamber airtight. Hence, the device increased in size because the opportunity of contact with the drawable material to be drawn increased. Hence, the device was apt to get into trouble on quality and operation. There was a difficulty when the drawable material was exchanged to a different type one. The cost of equipment was high. Moreover, the device was only put into practical use in the condition of a steam pressure range of from 2 to 3 Kgf/cm2 and a temperature range of from 120xc2x0 C. to 133xc2x0 C.
In order to solve the aforementioned problem, the inventors"" eager examination has resulted in the following invention.
An object of the present invention is to provide a device for drawing a drawable thermoplastic resin material, in which: the device can be adapted flexibly to exchange of materials when the drawable thermoplastic resin material to be drawn is exchanged in kind; there is no operational trouble; the device is so compact that the cost of equipment is low; and the drawable thermoplastic resin material can be drawn stably and uniformly with high quality under a high temperature.
Another object of the present invention is to provide a device for drawing a drawable thermoplastic resin material, in which the device can be speedy and surely adapted to the change of the sectional shape or sectional area of the drawable thermoplastic resin material by a simple operation even in the case where the sectional shape of the drawable thermoplastic resin material is changed into a circle, a film, aband, a sheet, a square, or the like, or in the case where the sectional area is changed.
The basic configuration of the present invention to achieve the foregoing objects is as follows.
A first invention is a device for drawing a drawable thermoplastic resin material, comprising: a laterally long drawing tank; a first pressurizing medium tank and a first buffer medium tank sequentially adjacently or closely disposed on an upstream side of the drawing tank; a second pressurizing medium tank and a second buffer medium tank sequentially adjacently or closely disposed on a downstream side of the drawing tank; first and second upstream ports for connecting the drawing tank to the respective upstream side tanks adjacent thereto successively; a third upstream port disposed on an upstream side of the first buffer medium tank; first and second downstream ports for connecting the drawing tank to the respective downstream side tanks adjacent thereto successively; a third downstream port disposed on a downstream side of the second buffer medium tank; a pressurized steam supply unit and a drawing tank discharge unit connected to the drawing tank; a pressurizing medium supply unit and a pressurizing medium discharge unit connected to the first and second pressurizing medium tanks; and a buffer medium supply unit and a buffer medium discharge unit connected to the first and second buffer medium tanks; wherein: opening members each having an opening which is formed substantially along the sectional shape of a drawable material passing therethrough with a slight gap therebetween are disposed, with their centers aligned, at the upstream and downstream ports; a pressurizing medium is allowed to flow in a slight amount into the drawing tank and the first and second buffer medium tanks through the first and second upstream ports and the first and second downstream ports; and an undrawn material supplied from the third upstream port is introduced into the drawing tank into which pressurized steam is introduced and which is kept airtight, is drawn and is led to the third downstream port for withdrawing.
Each of second to sixth inventions is a desirable mode as follows.
In the second invention, a heater is provided in the drawing tank and/or the pressurized stream supply unit so that heating control of an internal atmosphere of the drawing tank can be made.
In the third invention, a reservoir tank communicating with the drawing tank is provided as the drawing tank discharge unit, the liquid level of the reservoir tank is detected by a liquid level sensor, and a valve controller to adjust a valve automatically is actuated, to thereby make it possible to keep the drawing tank airtight.
In the fourth invention, the steam supply unit is formed so that the temperature of the inside of the drawing tank is detected by a temperature sensor, and a valve controller is actuated to adjust a valve automatically to thereby make it possible to keep the inside of the drawing tank at a desired temperature.
In the fifth invention, a packing member is used as each of the opening members and is selected from the group consisting stainless steel as a metal, and fluororesin and silicone resin as plastics.
In the sixth invention, the pressurized steam to be used is composed of water vapor, the pressurizing medium is composed of pressurized water, and the buffer medium is composed of low-pressure water lower in pressure than the pressurized water.
Each of seventh to thirteenth inventions is another desirable mode provided with a sealing device as follows.
The seventh invention is a device for drawing a drawable thermoplastic resin material further comprising a sealing unit disposed between each of the pressurizing medium tanks and adjacent one of the buffer medium tanks, the sealing unit including: a sealing portion constituted by a pair of upper and lower sealing rollers and a pair of side surface sealing plates, the pair of sealing rollers being disposed with a slight gap in a wall surface of a pressurizing tank side fitment fixed to an end surface of the pressurizing medium tank and having a slit formed in its center portion, the pair of sealing rollers being rotatably supported by swing levers pressed by pressing members, the pair of side surface sealing plates being fixed to the pressurizing tank side fitment while being in contact with left and right end surfaces of the sealing rollers; and a slit portion having a buffer tank side fitment, and a shutter, the buffer tank side fitment being fixed to the end surface side of the buffer medium tank adjacent to the pressurizing medium tank and having a slit in its center portion, the shutter being fixed to the buffer tank side fitment and having an opening portion formed with a slight gap substantially along the sectional shape of the drawable material passing therethrough; wherein the slits and the opening portion are disposed in accordance with the passage line of the drawable material so that the amount of the pressurizing medium leaking out can be kept very small by the sealing portion.
According to the eighth invention, the shutter is cut into two at its vertical center portion so that an upper shutter and a lower shutter each of which is shaped so as to be a rectangular plate are formed; vertical guides having vertical facing surfaces are disposed with a distance in the left and right of the upper and lower shutters; and the opening portion is set by adjustment of the vertical gap between the shutters sliding along the vertical guides respectively.
According to the ninth invention, the drawing device further comprises a slit up/down adjuster so that the vertical gap between the shutters can be adjusted by vertical movement of the upper shutter.
According to the tenth invention, the drawing device further comprises a width adjusting portion so that the lateral gap can be adjusted by lateral sliding of width adjusting materials.
According to the eleventh invention, the drawing device further comprises a slit left/right adjuster so that the lateral gap can be adjusted by lateral sliding of width adjusting materials.
According to the twelfth invention, the drawing device further comprises a pressing unit including pressing members attached to a pair of pressing shafts disposed on lower sides of support plates so as to face the upper shutter and/or width adjusting materials to thereby make it possible to press the upper shutter and/or width adjusting materials.
According to the thirteenth invention, a low-frictional plastic sheet material is fixed to any one of the contact surfaces of the side surface sealing plates with the end surfaces of the sealing rollers, the facing surfaces of the upper and lower shutters and the facing side surfaces of the width adjusting materials.
A fourteenth invention is another desirable mode in which the drawing device further comprises rod-like guides disposed in the passage position of the drawable material on the upstream side of the first buffer medium tank and/or on the downstream side of the second buffer medium tank and formed into such a shape that the lateral width between the guides is tapered downward in front view, so that the drawable material to be passed can be moved sideways.